Spectrophotometric simultaneous determination of mefenamic acid and paracetamol in combined tablet dosage form by dual wavelength, area under curve and absorbance corrected method

Three simple, economical, precise and accurate methods are described for the simultaneous determination of Mefenamic acid (MFA) and Paracetamol (PCT) in combined tablet dosage form. The first method (Method A) is Dual wavelength, second method (Method B) is Area under curve and third method (Method C) is Absorption Corrected . In the First method, MFA was determined by plotting the difference in absorbance at 234.73 and 260.70 nm (difference is zero for PCT) against the concentration of MFA. Similarly for the determination of PCT, the difference in absorbance at 243.5 and 267.79 nm (difference is zero for MFA) was plotted against the concentration of MFA in combined formulation. In second method wavelength ranges of 233.017-236.34 nm and 267.79-271.0 nm were selected to determine PCT and MFA by AUC method in combined formulation. In the third method MFA concentration was determined directly from calibration plot by measuring absorbance at 343 nm and PCT was determined after correction for absorbance of MFA at 233 nm. The methods were validated by following the analytical performance parameters suggested by the International Conference on Harmonization (ICH). Beer’s law is obeyed in the concentration range of 5-25 μg/mL for MFA and 4.5-22.5 μg/mL for PCT by both the methods.